Material for bearings, knife edges, and the like



knife edges and the like having the char-*- I Patented June 20, 1933 .UCNITED sTATasfPATaNr OFFICE WILLIAM BUBR, OF TOLEDO, OHIO, ASSIGNOR" T0 TOLEDO SCALE MANUFACTURING COMPANY, OF TOLEDO, OHIO, A CORPORATION OF NEW JERSEY I MATERIAL FOR BEARINGS, KNEE EDGE B, AND 'IHE LIKE No Drawing.

Another object is the. production of aprocess for obtaining metal for bearings,

acteristics mentioned above.

Other objects and advantages will be apparent from the following description.

In carryingout my process for making improved. material and knife, edge pivots, bearings andthe like therefrom, I employ steel of substantially the following composition:

7 Percent Carbon s; Silicon l .7 to .9 Manganese .5 to .7 Chromium 7. 5 to 8.5 Tungsten 7.5 to 8.5

The remainder being iron, which. may contain small amounts of impurities such as phosphorus, silicon and sulphur.

Specifically, I prefer to employ the following: Percent Carbon -1- Silicon .80 Manganese .60 Chromium 8.00 Tungsten 8.00

The remainder being iron, which may contain small amounts of impurities such as phosphorus, silicon and sulphur.

This steel is first formed into the shap'e-of the bearing, pivot or other part to be produced by any convenient method subh as forging, rolling, drawing or machlning. The formed pieces are then heated to a temperature of 2100 to 2200 degrees Farenheit and quenched in oil. They are then ground to remove all decarburization from the surfaceswhich are to be hardened. The pieces Application filed Kay 18, 1930. Serial No. 453,105.

so treated have a hardness of .600 to 650 when tested by the Brinnell machine and are very rust resistant.

' pieces In order to provide a wearing surface of great hardnes, the pieces are next subjected to nitriding by being placed in a retort which is brought to a temperature of 975 to 1100 degrees which a streamof The parts are kept in the retort and subjected to theinflue nce of the ammonia gas for a period of one or more'hours. Fourhours treatment results in the formation of a very thin, hard wear-resistant case. The pieces so treated will not exhibit any greater hardness when tested with the Brinnell machine than untreated pieces, but the surface cannot be braided by a file and is little affected even by long wear. The hardness of the case as determined by testing with a Vickers machine and the result converted by calculation into values according to the Brinnell system is from 900 to 1100. While hich have been treated do not exhibit an greater hardness under the Brinnell test than untreated pieces, on the other hand the core is not perceptibly softened by Farenheit and through ammonia gas is passed.

the heating to which it is subjected during I the treatment with ammonia.

The embodiment of my invention herein described is to be regarded as illustrative only, and it is to be understood that the in- 'vention .is susceptible to variation, modification and change within the spirit and I scope of the subjoined claims.

Having described myinvention, I claim: 1. An article of manufacture having a steel core of approximately the formula Percent Carbon .5 to .7 Silicon .7 to .9 Manganese .5 to .7 Chromium 7.5 to 8.5 Tungsten-Au. 7.5 to 8.5

The remainder being iron, which may containsmall amounts of impurities such as phosphorus, silicon and sulphur,

and a surface hardened by'treatment with ammonia at an elevated temperature.

' 2. An article of manufacture being 1 steel core of the formula rm Carbon 5 Silicon 80 Y Manganese 60 Chromi 8. 00 Tungs n 8. 00

The remainder being iron, which may contain small amounts of im urities such as phosphorus, silicon and sulp ur,

and a surface hardened by treatment with ammonia at an elevated temperature.

16 WILLIAMJ. BUBB; 

